Review of problems and their technical solution

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No [818242 — GEOENVI]

Review of problemsand their technical solutionPreventive and corrective mitigation measures

Adele MANZELLA

and the GEOENVI Team (CNR, BRGM, ISOR, CSGI, VITO, Enel GP, Rete Geotermica, ES-Géothermie, EGEC,DEU, MBFSZ )

[email protected]

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MITIGATION MEASURES

GEOENVI WebinarJune 30, 2020

Mitigation is an integral regulatory procedure in all international interpretations of environmental impact assessment (EIA). It spans three

forms of measures*:

• Prevention, which means that the potential impact is prevented or reduced before it occurs.

• Corrective measures, reducing the impact to a level which is acceptable**.

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A SYSTEM TO REDUCE, AVOID OR OFFSET THE POTENTIAL ADVERSE ENVIRONMENTAL CONSEQUENCES OF DEVELOPMENT ACTIVITIES

If preventive or corrective measures fail, then compensatory measures are applied. They will compensate for the unavoidable impact.

*European Environmental Impact Assessment Directive** See regulation

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GENERATION TECHNOLOGIESDEEP GEOTHERMAL DEVELOPMENT


A main aim is to have only positive impacts and no risks.

• 1st rule: prevention. The avoidance is made possible, in most cases, by considering potential negative effects in an early stage of the project

design processes and avoiding them using alternatives and preventive tools

This is not always possible, hence

• 2nd rule: mitigate any possible risk and negative impact (environmental, economical) while maximising positive impacts (beside electrical

power and heat production, increased touristic by-products or other, undirect, financial and societal benefits)

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MITIGATION MEASURES


Mitigation is practiced within or in the surrounding of

the site of development. It affects the development, its

construction and operation, and, in specific cases, its

products and processes.

All phases of a geothermal project can potentially have

an environmental implication, which requires to be

accounted.

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DEEP GEOTHERMAL DEVELOPMENT Exploration

•Exploration of

subsurface by

indirect data

(geophysical,

geochemical

and geological

data acquisition

and analysis)

•Exploratory

drilling and

resource

confirmation

•Reserve

estimates and

preliminary

design

Development

•Building access

roads and

drilling pad

•Drilling of

injection-

production

boreholes and

production

tests

•Stimulation

•Laying of pipe-

and

trasnmission

lines

•Surface

installations

Operation

•Production of

electricity/heat

•Drilling of new

wells

• Inhibitor

injection

•Stimulation

•Mantainance of

installations

and boreholes

(work over)

Decommissioning and abandonment

•Deconstruction

of surface

facilities

•Sealing,

permanent

plugging of

wells

•Material

disposal

•Site clearance

and restoration

•Monitoring of

installations

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A REPORT ON MITIGATION MEASURES


A report from the GEOENVI project, reviewing thecurrent best practices and available technologies toavoid, whenever, possible, or otherwise minimise theunavoidable effects to the environment produced bygeothermal development

https://www.geoenvi.eu/publications/report-on-mitigation-measures/

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ADOPTED SOLUTIONS TO OVERCOME ENVIRONMENTAL CONCERNS RELATED TO GEOTHERMAL DEPLOYMENT


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A REPORT ON MITIGATION MEASURES


Reviewing:

• Monitoring technologies, to establish the level and

intensity of impacts and risks

• Controlling technologies to avoid that acceptable

standards are not exceeded

https://www.geoenvi.eu/publications/report-on-

mitigation-measures/

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ADOPTED SOLUTIONS TO OVERCOME ENVIRONMENTAL CONCERNS RELATED TO GEOTHERMAL DEPLOYMENT


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A REVIEW OF MITIGATION MEASURES


Events that needs control and mitigation have been

ranked and analysed.

The described scenario is a worst-case one, where all

potential problems occur at the highest grade.

In reality this is far from representing a real case, as

many impacts and risks are accidental or restricted to

very defined geological condition or technologies.

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Effects associated to

surface operations

Energy and water

consumption and emissions

to the environment

Waste production from

surface operations

Surface disturbance,

including vibration, noise,

…

Leaks due to surface

installations and operations

Effects associated to emission of

underground material to the

surface

Liquid/solid effusions and

waste

Degassing

Radioactivity

Blowout

Effects associated to

geomechanicalchanges

Ground surface deformation

Seismicity

Effects associated to underground physical and

chemical modifications

Pressure and flow change

Interconnection of aquifers and disturbance of non-targeted

aquifers

Thermal changes

DEFINITION OF THE PROBLEM

EFFECTS ASSOCIATED TO

SURFACE OPERATIONS

/ GEOENVI WebinarJune 30, 20209

EFFECTS ASSOCIATED TO SURFACE OPERATIONS

ENERGY AND WATER CONSUMPTION AND EMISSIONS TO THE ENVIRONMENT

Monitoring:• Energy use and losses and water consumption

Prevention and corrective measures:• Planning optimal use since the beginning.• Use of local electricity generation, alternative power supply.• Recirculation of drilling mud to reduce water consume, meteoric water

collection, discharged geothermal fluids or low-quality water used as make up fluid



WASTE PRODUCTION

Monitoring:• Official log of waste production and periodical report to the regulating

authority• Regular inspection, to check for proper management and for the regular

functioning of containment basins

Prevention and corrective measures:• Careful design to minimise the waste and treatment of unavoidable waste

during the operations • Proper tanks, basins and areas, segregated from other materials and

equipment• Waste recycling or disposal toward the appropriate treatment plant• Hazardous waste (such as oils and batteries) is stored in segregated and

labelled containers • Waste-water is either collected or connected to sewage



LAND OCCUPATION, VISUAL, NOISE, VIBRATION, DUST, SMELL

Monitoring:• Seismic sensors for vibration, • Acoustic characterization before and during operations, • Smell assessment (in development)

Prevention and corrective measures:• Landscape planning, pipes’ layout, choice of drilling rig to reduce the height

of the rig and the pad’s occupied land, cover for well-head.• Planning for optimal noise reduction: muffled materials and insulation,

activities’ timing; information to population for unavoidable temporary emissions.

• Prevention of dust dispersion by cleaning, water spray, use of water channels for transport.

• …



LEAKS

Monitoring:• Periodical inspection of pipes and tanks• Check the occurrence and evolution of corrosion and scaling

Prevention and corrective measures:• Tanks big enough to avoid overflow and positioning tanks over concrete slab

to avoid direct contact with soil• Pipes and tanks’ material chosen as to avoid corrosion problems, or use of

coatings, anti-corrosion products• Chemicals are stored in segregated areas with containment basins, to avoid

and contain, in disastrous condition, any spill• Proper choice (environmental benign) of secondary fluids and chemical

inhibitors


EMISSION OF

UNDERGROUND MATERIAL

TO THE SURFACE


EFFECTS ASSOCIATED TO EMISSION OF UNDERGROUND MATERIAL TO THE SURFACE

LIQUID AND SOLID EFFUSIONS ON SURFACE

Monitoring:• Sampling and analysis for target contaminants at each intermittent as well

as continuous discharge points (wellheads, vents, and separators, cooling towers and spent liquid drains)

• Waste, surface waste-water monitoring,

Prevention and corrective measures:• Collection and disposal of any material produced from drilling • Any short-term and/or emergency liquid releases are accommodated in a

special holding tank or a holding pond during all phases of geothermal development, which are emptied periodically

• Non-polluting drilling fluid additives and mud recycling • Fluids are reinjected back into the underground or treated and disposed (if

allowed by local regulation). Treated with biocides and/or oxygen scavengers in case of contact with oxygen

• Effective water management



DEGASSING

Monitoring:• At three main levels: emissions control at the power plant, air quality

monitoring in the surrounding environment, and changes in natural gas/temperature emission from the soil

• Before and during operation• Periodic (common) or continuous (permanent network)

Prevention and corrective measures:• Preventers to avoid accidental releases• Complete capture and reinjection of fluids, hybrid technologies • Where total reinjection is beyond actual commercial technology, abatement

systems• CO2 reinjected (low rate) or captured and utilised (e.g. for soda waters,

agriculture etc.)• Methane separated and burned for local electricity production• Drift eliminators • Minimum duration of unavoidable degassing (e.g. production tests)

following the strictest maintenance protocol (well trained personnel)



RADIOACTIVITY

Monitoring:• Recording of background condition, possibly before the industrial

development, and at the geothermal installations by radiometers, contamination detector

• Period monitoring of samples from the filter elements and the scaling as well as the geothermal water

Prevention and corrective measures:• Adopting of radiation protection measures to guarantee a zero or minimum

level of exposure to visitors• NORM (Naturally Occurring Radioactive Material) are treated following the

radioactive waste management rules of the country. Only specialized companies can manage these residues

• Total reinjection of fluids and prevention for scales



BLOWOUT

Monitoring:• Sensors to display critical parameters during drilling operations• Continuous check in order to notice early warning signs of potential blow-

outs

Prevention and corrective measures:• Blowout preventers (BOP) installed• Good drilling practices and well-trained personnel• Preventive measures ( in the case of high ratio of non-condensable gases in

the steam (mostly CO2), or where the geothermal reservoir is over pressurized, such as high density drilling mud, casing strategies


GEOMECHANICAL

CHANGES


EFFECTS ASSOCIATED TO GEOMECHANICAL CHANGES

GROUND SURFACE DEFORMATION

Monitoring:• Geodetic techniques (modern remote sensing technologies)• Benchmarks installed throughout the geothermal field and surveyed at

regular interval (GNSS, levelling, or total stations)

Prevention and corrective measures:• Prediction based on the numerical modelling of reservoir performance • Injection of fluids in the geothermal reservoir to control land subsidence • Extraction rate control to mitigate surface deformation


EFFECTS ASSOCIATED TO GEOMECHANICAL CHANGES

SEISMICITY

Monitoring:• Seismic network (seismometers), continuous recording • Before and during operation

Prevention and corrective measures:• Probability assessments of hazard and risk of induced seismicity• Balance between produced and reinjected fluid and minimize pore pressure

changes at depth • Reactive protocols (e.g. traffic light systems) and operational protocols to

mitigate the effects of an event if one should occur, by further control or, in some case, suspending activities

UNDERGROUND PHYSICAL

AND CHEMICAL

MODIFICATIONS


UNDERGROUND PHYSICAL AND CHEMICAL MODIFICATIONS

PRESSURE AND FLOW CHANGES

Monitoring:• Regular monitoring of pressure, temperature and production in geothermal

wells, chemical samples and tracer tests• Specialised tests (e.g. step tests) to verify evolution of reservoir conditions,

for decision making• Periodic wells shut-down for pressure check and pipe cleaning

Prevention and corrective measures:• Injection and re-injection of fluids in the reservoir to replace the volume of

extracted fluids; injection strategy • Prevention of reinjection failures (accumulation tank to guarantee a

constant injection flow rate, pipe cleaning)• Recovery of pressure by letting some wells to rest while others are used,

exchanging modes with time (“harnessing” the resource)



INTERCONNECTION OF AQUIFERS AND DISTURBANCE OF NON-TARGETED AQUIFERS

Monitoring:• Casing condition (effects of corrosion, thermomechanical and other

disturbances on the casing in the wellbore)• Flow rate, pressure and water quality are monitored during the operation

phase to identify potential leakage • Quality of cementing work during and after drilling • Piezometric and water quality control of the aquifers above the developed

geothermal reservoir

Prevention and corrective measures:• Optimal well design (material, casing)• Optimal drilling work, cementation and casing implementation • Corrective well operations and work-over using patch or new casing



THERMAL CHANGES

Monitoring:• Temperature logs in monitoring wells

Prevention and corrective measures:• Balance of fluid extraction with the natural inflow of water and reinjection• Careful siting of injection wells

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FINAL COMMENTS


• Monitoring is common practice, and data are checked against established limit values

• All the environmental effects analysed are well documented and mitigation measures have proven to be effective.

• Research and Innovation is proceeding and innovative solutions are continuously improving the environmental friendliness

of the geothermal technologies.

• It is possible to keep geothermal industrial development safe and sound.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No [818242 — GEOENVI]

https://www.geoenvi.eu

Thank you for your attention

Documents

Review of problems and their technical solution